This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A211877 #16 Aug 23 2013 13:57:33
%S A211877 1,21,673,102273,47663617,110981851137,815432848809985,
%T A211877 30052835284679819265,3519512226295269640765441,
%U A211877 2069751512310185039905834926081,3874510079394593253089862950754189313,36431456010689490638771956423547489198538753
%N A211877 Number of involutions in GL(n,4).
%H A211877 Alois P. Heinz, <a href="/A211877/b211877.txt">Table of n, a(n) for n = 1..50</a>
%p A211877 A211877 := proc(n)
%p A211877 add( 4^(k*(n-k))*A022168(n,k),k=1..n) ;
%p A211877 end proc: # _R. J. Mathar_, Apr 26 2013
%t A211877 Sum[q^(k (n - k)) QBinomial[n, k, q], {k, 1, n}]
%K A211877 nonn
%O A211877 1,2
%A A211877 _Alexander Gruber_, Feb 12 2013